Adsorption of contaminant gases and vapors onto activated carbon is an important process used for sampling, indoor air cleaning and respiratory protection. In most environments where these applications are used the gas phase contaminants are present in small concentrations and usually in mixtures. Water vapor is ubiquitous in most environments and is adsorbed together with the gas phase pollutant. Often the pollutant itself represents a mixture of gases, vapors, or both. The performance of the adsorbent respective to a gas or vapor is changed when a second component is co-adsorbed. The extent of this process is not yet well documented or understood, especially when the components of the mixture are present in low concentrations. The proposed research will experimentally investigate the changes in the adsorption capacity of three types of activated carbon when challenged with individual gases and vapors, and with low concentration gas phase contaminant mixtures. In almost all cases the presence of a second component will diminish the adsorption capacity of the carbons, with some notable exceptions which will be considered in this study. The changes in the adsorption performances of activated carbons will be quantified using parameters such as adsorption capacity, adsorption rate constant and mole fraction of the adsorbed phase. The research also proposes to use the experimental data in the development and validation of simple, applicable models able to predict the performance of the activated carbon for the components of a mixture from individual component adsorption data. The goals of the proposed project are to 1)review the literature for information on adsorption studies and models, 2)conduct a series of adsorption tests on selected gas phase contaminant mixture systems to assess the impact of low concentration components on the adsorption, 3)develop adsorption models based on the relationship between the adsorption performances and various parameters of the components in the mixture.